For instance, from German Patent No. 195 34 445, a fuel injector is known which has an axially movable valve needle in a nozzle body. The valve needle is able to be actuated by a piezoelectric actuator and held in the closing position by a compression spring. The fuel is supplied by an external source at a freely adjustable pressure. The valve needle has a central bore. The piezoactuator concentrically surrounds the valve needle and is sealed from the fuel pressure by sealing surfaces.
Disadvantageous in the fuel injector known from German Patent No. 195 34 445 is, in particular, that the encapsulation of the piezoelectric actuator, which must be sealed from the corrosive fuel and the pressure of the fuel, is labor intensive and expensive. In addition, it is difficult to compensate for thermal longitudinal changes in the actuator in order to avoid subsequent malfunctions of the fuel injector.